The O-alkyl and alk-l-enyl lipid content of whole tumor and tumor plasma membranes will be measured in metastasizing and non-metastasizing transplantable rat mammary tumors. Preliminary work with these lines suggests that the metastasizing tumors have a higher O-alkyl lipid content than the benign counterparts. Previous data, obtained from Ehrlich ascites tumor cell plasma membranes, show a higher O-alkyl lipid content in the plasma membrane than in other cellular fractions. We are currently evaluating the catabolism of acyl dihydroxyacetone phosphate as this relates to the previously demonstrated hydrogen release and to the mechanism of ether lipid bond formation.